Overdose : מינון יתר

4.9     Overdose

4.9.1    Toxicity

Accidental intravascular injections of local anaesthetics may cause immediate systemic toxic reactions. In the event of overdose, systemic toxicity appears later (15–60 minutes after injection).
Toxicity is manifested first in the central nervous system, then followed by the cardiovascular system. In paediatric patients, when a local anaesthetic is administered under general anaesthesia, it is difficult to detect the first signs of toxicity to the local anaesthetic.

Central nervous system toxicity
Initially, symptoms include agitation, a feeling of intoxication, a sensation of numbness in the lips and tongue, paresthesias around the mouth, dizziness, vision and hearing disturbances, and buzzing in the ears. Speech problems, muscle stiffness and spasms are more serious symptoms and precede generalised seizures. Respiratory arrest may even occur in severe cases. Acidosis increases the toxic effects of local anaesthetics. Recovery depends on the metabolism of the local anaesthetic and the distribution away from the central nervous system. This occurs quickly providing large amounts of the drug are not injected.

Cardiovascular system
The symptoms associated to the local anaesthetic may include blood pressure drop, bradycardia, arrhythmia, and cardiac arrest as a result of high systemic concentrations of local anaesthetic.
The symptoms associated to epinephrine are heat sensation, sweating, heart rhythm acceleration, headaches, blood pressure increase, anginous disorders, tachycardia, tachyarrhythmia, and cardiac arrest.

LIDOCADREN TEVA RH SY 03.2016
4.9.2    Treatment

General basic measures
If adverse reactions arise the application of the local anaesthetic has to be stopped. Measures should focus on maintenance/restoration of the vital functions of respiration and circulation, oxygen administration and intravenous access.

Special measures
- Hypertension: Elevation of the upper body, if necessary sublingual nifedipine.
- Seizures: Protect patients from concomitant injuries, if necessary benzodiazepines (e.g.
diazepam IV).
- Hypotension: Horizontal position, raise legs up, if necessary intravascular infusion of a complete electrolyte solution IV, vasopressors (e.g. ethylephrine IV).
- Bradycardia: Atropine IV.
- Anaphylactic shock: Infusion of a complete electrolyte solution, if necessary epinephrine IV, cortisone IV; contact emergency physician.
- Cardiovascular arrest: Immediate cardiopulmonary resuscitation, contact emergency physician.